Analysis On GST-proteins Interaction And The Differential Expressing Proteins In The Root Of Rice (Oryzu Sativa L.) Under Cadmium Stress

As a result of wastes disposal from numerous industry and agricultural activities, agricuturalsoil pollution by heavy metals like cadmium has become increasingly serious. Cadmium isnon-essential and toxic heavy metal element for plant growth and development. High cadmiumconcentration in soil has a serious effect on crop growth and development, and can decline cropquality and yield. Much research work had been carried out to analyze the detoxificationmechanisms of cadmium by plant. However, few work had been conducted to studyprotein-protein interaction in the root of rice under cadmium stress. In this study, two ricevarieties, Shanyou63Nipponbare, with different ability to avoid cadmium stress, were employedas materials. First, differential expressing protein in the root of rice in response to cadmiumstress was analyzed by two-dimension Eletrophoresis (2-DE), MALDI-TOF-TOF-MS andMASCOT database searching tools. Second, the differentially expressing protein complex in theroot of rice under cadmium stress was studied by Native-PAGE and Pull-down.1. The cadmium content in the root of rice under cadmium stress was determined by AtomicAbsorption Spectrometry(AAS). The result showed that cadmium accumulation was greatlyincreased in two rice cultivars under cadmium stress, compared with the Control. Under3,5,7dstress, cadmium content in the root of Shanyou63were97,72,41higher than the Control, whileNipponbare were105,107,98higher than the Control. Meanwhile, the cadmium content in theroot of Nipponbare was significantly higher than that in Shanyou63, indicating that Shanyou63possesses better ability to avoid cadmium stress than Nipponbare. With cadmium stress dayextended, cadmium content in the two rice cultivars declined, suggesting that rice plant graduallydeveloped the detoxificating ability to decrease cadmium uptaking or transport cadmium toextracellular region.2. Two-Dimension Electrophoresis and MOLDI-TOF-TOF-MS were applied to analyze thedifferentially expressing proteins in the root of rice under cadmium stress. Fourteen proteins inthe root of Shanyou63and Nipponbare were found to be regulated by cadmium stress, ten of14proteins were up-regulated and4of14proteins were down-regulated. The expressing abundanceof10up-regulated proteins in Shanyou63were all higher than that in Nipponbare. By GeneOntology analysis, ten up-regulated proteins were involved in energy metabolism, anti-stressprogress and material sythesis. Three of4down-regulated proteins were relevant to energy metabolism, anti-stress progress and material sythesis, respectively. This result showed thatcadmium stress suppressed material sythesis and transport in rice plant, promoted the ability ofrice plant to avoid cadmium stress, and maintained rice plant normal growth.3. Protein-protein interaction in the root of rice under calmium stress was analyzed by usingNative-PAGE, His-Pull down and LC-MS-MS. One differentially expressed protein complexwas found in two rice cultivars, which was comprised of4different GSTs proteins,1disulfideisomerase protein and2cysteine synthase protein. GSTs proteins could catalyze Cd2+bindingwith GSH and form Cd2+-GSH complex, which was transported out of cellular or into vacuole.Cysteine synthase and protein disulfide isomerase promoted sythesis of cystein and theformation of disulfide, repectively. This result indicated that calmium stress induced theinteraction of GSTs proteins, protein disulfide isomerase and cysteine synthase in rice root totransport cadmium to extracellular space or into vacuole.In conclusion, Shanyou63exhibited better abilty to avoid cadmium stress than Nipponbare,but the calmiun content in the two rice varietie with different ability to avoid calmium stressdecreased with the calmium stress extending Our result illustrated that GSTs proteins playedimportant role in rice plant to tolerance to cadmium stress. Calmium stress induced GSTSproteins interacting with disulfide isomerase and cysteine synthase, up-regulated the expressingabundance of proteins which were involved in energy metabolism, anti-stress progress, materialsythesis, then transported cadmium to extracellular space or into vacuole.